This invention relates to a heat exchanger used in an oil cooler or a heater core mounted on an automobile, or for an evaporator or a condenser in an air conditioner, for example, an automotive air conditioner, and, in particular, to a heat exchanger with fluid control means for controlling a flow of a heat transfer medium. This invention also relates to a method of manufacturing the heat exchanger of the type.
Generally speaking, an internal fluid flowing through a pipe is heat-exchanged with an external fluid outside the pipe. The internal fluid is called a heat transfer medium which transports heat or cold between two areas. On the other hand, the external fluid is a fluid such as air, liquid and other fluid to be heated or cooled. In an air heating system, the heat transfer medium is a heat carrier such as a steam or a warm water which transports heat, while the external fluid is air. In an air cooling system, the heat transfer medium is called a refrigerant for cooling the air by the heat exchange therebetween. The air to be heated or cooled will often be referred to as a heat exchange air.
A first conventional heat exchanger comprises a pair of tanks, a plurality of tubes connecting those tanks each other, and a plurality of fins arranged and attached onto the tubes. Each of fins has an outer surface exposed to the external fluid to be heat-exchanged, for example, air in the air heating and/or cooling system.
The heat transfer medium is flown through the tubes from one of the tanks to the other. The heat or cold transported by the heat transfer medium is given to the air through the tube and fins. Therefore, the tubes and the fins are often referred to as heat exchange tubes and heat exchange fins, respectively. The heat exchange fins are for increasing the area of a heat exchanging surface with which the air comes into contact so as to receive the heat or cold.
The tubes and the fins are alternately arranged and assembled to form an integral structure. Each of the tanks is composed of a combination of a tank base member and a tank cover member. Each tank base member is connected to open ends of the tubes.
The tanks are provided with the fluid control means which comprises a single partition member and a plurality of flow regulation members.
The single partition member has a flat plate shape and is arranged in first one of the tanks at an approximate center in the longitudinal direction and separates the inside of the first tank into two chambers independent from each other.
The flow regulation members are arranged in the first tank and the other, or second, tank. In the first tank, the two independent chambers are separated into a plurality of sections in a longitudinal direction by provision of the flow regulation members. The inside of the second tank is also separated into a plurality of sections by the flow regulation members. Each of the flow regulation members has a hole formed in the center to communicate between sections at both sides of the flow regulation member. This hole serves to regulate the flow of the medium therethrough from one side to the other side of the flow regulation member, so that a liquid phase and a gas phase of the heat transfer medium are well mixed to provide a uniform flow of the medium. The flow regulation members are arranged at a predetermined space from one another. The single partition member and the flow regulation members are, at their peripheral portions, fixed to inner walls of the tanks by brazing.
One of the chambers in the first tank, which will be referred to as an inlet chamber, is connected to an inlet pipe for introducing the medium thereinto and the other chamber, which will be referred to as an outlet chamber, is connected to an outlet pipe for discharging the medium therefrom.
In the heat exchanger described above, the medium flows into the inlet chamber of the first tank through the inlet pipe. Then, the medium flows from the first tank into the second tank through the tubes, thereafter returns from the second tank to the outlet chamber of the first tank through the tubes, and finally flows out from. the outlet chamber through the outlet pipe. In the meanwhile, the air flows through gaps between adjacent fins. Heat exchange is performed between the air and the medium flowing through the tubes.
In first conventional heat exchanger, the internal wall surface of each tank is cut to form a plurality of fitting grooves for fitting the single partition member and for the flow regulation members at predetermined positions. After the partition member and the flow regulation members are fitted into the fitting grooves, they are brazed to the internal wall surfaces of the tanks.
However, the above-mentioned first conventional heat exchanger is disadvantageous in that the fitting grooves are formed by the cutting process which requires great skill and is uneconomical.
In a second conventional heat exchanger, the cover member is formed with the fitting grooves by the deep drawing method. A single partition member and a plurality of flow regulation members are fitted in the fitting grooves in one-to-one correspondence and fixed by welding.
However, each fitting groove formed by the deep drawing process inevitably has a flared shape with rounded corners. In this event, the width of each fitting groove can not be made uniform in a depth direction. Specifically, the width is smallest and greatest at the bottom and the top of the groove.
The presence of the rounded corners results in a large clearance between the fitting groove and one of the single partition member and the flow regulation members that is fitted therein. Such a large clearance is difficult to be completely filled with a brazing member. This brings about vibration of such member in the fitting groove and deteriorates the reliability of brazing bond therebetween.
A third conventional heat exchanger is disclosed in Japanese Utility Model Publication (B4) No. H02-45667 (45667/1990). The heat exchanger comprises a pair of upper and lower tanks having a lower and upper opening portions, respectively, a pair of tube gathering plates arranged to cover the opening portions of the tanks, and a partition member dividing a tank cavity defined by one of the tanks and the corresponding one of the tube gathering plates.
A plurality of tubes are connected between the tube gathering plates. A plurality of fins are interposed between every adjacent ones of the tubes. On each tank, a reinforcing protuberance is formed to extend in a back-and-forth direction. An insertion hole is formed at the center of the protuberance to penetrate therethrough. The partition member has a projection formed at the center of an upper edge thereof to be fitted into the insertion hole.
The partition member is received within the internal space of the tank. The projection of the partition member is fitted into tide insertion hole. The upper edge of the partition member is brought into contact with the internal surface of the tank. The tank, the tube gathering plates, and the partition member are integrally bonded by brazing. At this time, the insertion hole is-sealed also.
A fourth conventional heat exchanger is disclosed in Japanese Utility Model Publication (B4) No. H07-29416 (29416/1995). The heat exchanger comprises a plurality of tubes for passing a heat transfer medium, a plurality of fins interposed between every adjacent ones of the tubes, a pair of tanks connected to the tubes and operable to introduce and discharge the medium, and a partition member dividing the internal space of each tank into a plurality of tank cavities independent from one another.
Each tank comprises a combination of a first tank plate and a second tank plate which can be separated in a radial direction. The first and the second tank plates are provided with positioning insertion holes and positioning fitting grooves to be engaged with the partition member.
The partition member is located between the first and the second tank plates to define the tank cavities. The partition member has a pair of engaging projections. The engaging projections are inserted into the insertion holes of the first and the second tank plates. Each tank and the partition member are integrally bonded by brazing. At this time, the insertion holes are sealed.
The projection of the partition member in each of the third and the fourth conventional heat exchangers is formed in a press-forming process of punching a single plate. As a result of punching, burrs are caused in a thickness direction of the plate. The presence of burrs makes it difficult to insert the projection into the insertion hole.
Specifically, as far as the projection has a configuration substantially same as that of the insertion hole to assure tight fit therebetween, the presence of the burrs prevents the insertion of the projection into the insertion hole.
Taking the above into consideration, the diameter of the insertion hole may be increased in order to smoothly insert the projection into the insertion hole. In this event, the clearance between the projection and the insertion hole is inevitably widened. Such a wide clearance can not completely be filled with a brazing member. This deteriorates reliability of the brazing.
Alternatively, the burrs must be removed before the projection is inserted into the insertion hole. This deteriorates the efficiency in assembling operation and increases the number of assembling steps.